I don't know if anyone has experimented with this. I never used 2 SD cards on the X-T2 before but Amazon had some cheap Sandisk cards (Ultra, UHS-I, 80MB/s) so I decided to give this a try, having my very fast Sandisk SD (extreme pro) card on slot 1 and this slower one on slot 2. These 2 cards have roughly the same read speed but the write speed differs quite a bit. My tests say 76MB/s on the Extreme Pro and 26 MB/s on the cheaper ones (Ultra). I can actually tell the difference if I shoot on CH and then time the time it takes to write to the card, that's roughly a factor of 3 like my test. I don't shoot video so I'm not interested in that. And very rarely I shoot in burst mode. Since my primary use for the extra card is to have the in camera backup (going to Iceland so I'm getting nervous about failures), does anyone see any disadvantage in having the 2 cards like this, super-fast on slot 1 and not so fast on slot 2? thanks.